1. Field of the Invention
The invention relates to a method and a device for discharging signature free exhaust gas from underwater vehicles, said exhaust gas being a by-product of the production of electric energy in energy converters, and to such an underwater vehicle.
2. Description of the Prior Art
When using hydrocarbons for delivering energy, energy converters, which serve to produce electricity in underwater vehicles without having to rely on outside air, not only produce electricity but also exhaust gas.
Said exhaust gas must be stored on board or discharged from the vehicle. The solutions heretofore proposed are water management systems, the liquefaction of the exhaust gas and subsequent storage thereof or the direct discharge in the form of gas.
The document EP 0 752 565 B1 for example discloses an apparatus for the disposal of CO2 in underwater vehicles. To dispose of the CO2 in underwater vehicles, pressurized water has to be ingested from the outside into the underwater vehicle where it dissolves CO2 with the assistance of an absorber after which this water, containing the dissolved CO2, is to be redirected out of the vessel against the immersion pressure.
According thereto, there is provided an apparatus that has a housing which is provided with a circular internal tread for a rotating cam body, said internal tread being disrupted by opposite pairs of water inlet ports and water outlet ports, each water inlet port being separated from the water outlet port by a vane that is radially slidable on the cam body and a respective one of the inlet ports for high-pressure water alternating with an outlet port for low-pressure water and a respective one of the inlet port for low-pressure water alternating with an outlet port for high-pressure water on the circular internal tread of the housing. This apparatus is characterized in that it is provided with but a few movable parts and sealing surfaces and that it permits, with low internal flow resistance and without flow reversal, harmonious flow of the water transported for the disposal of CO2, with the water bearing parts of the apparatus being treated with care and subjected to little strain as a result thereof.
In Schiff and Hafen/Seewirtschaft (Ship and Harbour/Sea Trade), Part 7/1992, pp. 43-46, the contribution xe2x80x9cDer Kreislaufdiesel als auxcex2enluftunabhxc3xa4ngiger Antrieb fxc3xcr U-Bootexe2x80x9d (Recirculation diesel as an air independent drive for submarines) describes a water management system that is suited to take in sea water for the absorbers and to release it again out of the vehicle. This water management system uses the energy of the sea water subjected to immersion pressure. The arrangement consists of control valves and of freely movable pistons that allow the diesel recirculation system to operate independent of the immersion depth. The feed pumps for the intake of sea water only need to compensate the resistances of the pipelines and of the fittings.
These systems require either lots of space or lots of energy or they result in signatures that make it easy to locate the underwater vehicle.
It is therefore the object of the present invention to discharge exhaust gas with low signature from the vehicle while requiring little space and energy.
In accordance with the invention, the solution of this objection is achieved by a method for discharging signature free exhaust gas from an underwater vehicle having an energy converter for producing electric energy, the exhaust gas being a by-product of the energy converter. The method comprises the steps of supplying outboard water to at least one pipe having a pipe length between an inlet and an outlet, directing the exhaust gas into the at least one pipe using pressure and generating gas bubbles of the exhaust gas in the at least one pipe, and reducing the generated gas bubbles so that the gas is dissolved by high turbulence of the output water in the at least one pipe using static mixers arranged in the at least one pipe.
Accordingly, the invention includes a method for discharging signature free exhaust gas from underwater vehicles, said exhaust gas being a by-product of the production of electric energy in energy converters and being directed by means of pressure into a pipe length through which outboard water is flowing. The thereby generated gas bubbles are reduced by means of static mixers arranged inside of the pipe length through which water is flowing, with the gas being dissolved by the high turbulence of the fluid.
As the exhaust gas is dissolved inside of the underwater vehicle, no gas bubbles that might be located are produced outside the vehicle. Since the working pressure of the method equals the immersion pressure, but little energy is consumed.
According to a preferred feature of the invention, the exhaust gas is introduced into the pipe length by way of a porous body, the exhaust gas being introduced into the pipe length at a pressure that preferably is above the immersion pressure.
The pipe length is thereby supplied with outboard water (sea water) by way of a pump. According to a particular feature, the pipe length is supplied with outboard water (sea water) by the moving underwater vehicle, the outboard water being subjected to immersion pressure between the inlet and the outlet point. According to another feature, the flow velocity of the water inside the pipe length preferably amounts to 1-3 m/s.
The invention also comprises a device for discharging signature free exhaust gas from underwater vehicles, said exhaust gas being a by-product of the production of electric energy in energy converters. For the purpose thereof, at least one pipe length is arranged in the underwater vehicle, said pipe length being provided with an inlet for outboard water (sea water), an outlet for the exhaust dissolved in the water, and an injection site for the exhaust gas to be introduced into the pipe length. At least one static mixer is provided inside of said pipe length. According to another feature, a pump is arranged in the region of the inlet port for the outboard water of the pipe length. In accordance with another feature of the invention, the injection site consists of a quadrant pipe with an injection lance and a porous body. According to a preferred feature of the invention, the length of the pipe is such that it allows complete dissolution of the gas bubbles of the exhaust.